1. Field of the Invention
The present invention relates to environmental control systems, and more particularity, to environmental control systems for multiple room structures having independently actuatable heating and cooling devices in each room.
2. Description of the Prior Art
The prior art discloses a wide variety of devices intended for use in multiple room structures such as hotels and motels and which reduce the heating or cooling load in unoccupied guest rooms. This reduction in heating and cooling load is accomplished by permitting the room temperature in unoccupied rooms to rise above the comfort level when the environmental control system is in the cooling mode and by permitting the temperature in unoccupied rooms to decrease below the comfort level when the environmental control system is in the heating mode.
U.S. Pat. No. 4,060,123 (Hoffman) discloses a device of the type described above which overrides the room heating and cooling unit thermostat to cause the room temperature to increase or decrease to an energy saving temperature when the room occupant removes the room key from the room control unit.
U.S. Pat. No. 4,021,615 (James) discloses an energy conservation system which enables a room clerk to transmit an audio tone over the telephone lines into each vacant guest room to turn off the room heating and cooling device. This system also permits a room clerk to turn on a room heating and cooling device just before the room is to be occupied. The James system is a passive system in that no information is transmitted from the room to the central control unit.
U.S. Pat. No. 3,934,797 (Perlmutter) discloses a temperature control system which incorporates a pair of thermostatically controlled switches within each room of a multi-room structure. One thermostat permits a first predetermined temperature to be maintained if a room is occupied while the second thermostat permits the room temperature to be maintained at a second level when the room is unoccupied. A clock controls the selection of one of the two thermostats and thus designates when the "occupied" thermostat will be actuated and when the "unoccupied" thermostat will be actuated.
U.S. Pat. No. 3,964,676 (Rooks) discloses an electronic morning start-up control for a building temperature control system. A cyclic clock starts a fixed period auxillary timer a predetermined time before building occupancy is to commence to permit the building temperature to be raised or lowered to a predetermined level by the time occupancy commences.
U.S. Pat. No. 3,945,564 (Smallegan) discloses a temperature control system which provides an automatic reduction in room temperature during night time hours.
U.S. Pat. No. 4,031,322 discloses a telephone operated signalling system which utilizes the twin conductor telephone wires which extend between the front desk of a motel or hotel and each individual room. This system permits maids and other employees to transmit signals to the front desk during clean up activities.
Other related inventions are disclosed in the following U.S. Pat. Nos.: 3,908,899 (Millard); 3,743,009 (Dagerford) and 3,933,197 (Zimmer et al).